program TheFourth;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  n, k, i, a, b, c: integer;

begin
  readln(n);
  readln(k);
  a:=1;
  b:=1;
  c:=1;
  if (n<k) then
    writeln('0')
  else
  begin
    for i:=1 to n do
      a:=a*i;
    for i:=1 to k do
      b:=b*i;
    for i:=1 to n-k do
      c:=c*i;
    writeln(a div (b*c));
  end;
  readln;
end.
